Method of manufacturing an assembled body composed of a plurality of members, manufacturing method of electromagnetic control valve, and control valve for variable capacity compressors

ABSTRACT

There is provided a brazing method which makes it possible to rationally perform not only the brazing between a metal member such as a stator made of a magnetic material and a metal member such as a guide pipe made of a non-magnetic material but also the magnetic annealing of these metal members. By making use of a brazing material ( 90 ) which can be fused at a lower temperature than a magnetic annealing temperature of metal member ( 33 ), the metal member such as a stator made of a magnetic material and the metal member ( 35 ) such as a guide pipe made of a non-magnetic material are heated to a predetermined temperature in a furnace to perform the magnetic annealing of the metal member ( 33 ) concurrent with the brazing of these metal members.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing an assembledbody composed of a plurality of components comprising a metallic membermade of a magnetic material, and a metallic member made of anon-magnetic material. The present invention also relates to a method ofmanufacturing an electromagnetic control valve which is constituted byan assembled body wherein a stator made of a magnetic metallic materialis fixedly coupled by means brazing to a guide pipe made of anon-magnetic metallic material and designed to be used as a plungerguide.

Further, the present invention relates to a control valve for a variablecapacity compressor to be employed in air conditioners for vehicle, inparticular, to a control valve for a variable capacity compressor, whichis suited for use in a crutch-attached compressor wherein thetransmission of rotating driving force from the engine to the rotatingaxis of compressor is effected by means of a crutch.

2. Description of the Related Art

As shown in JP Patent Laid-open Publication (Kokai) No. 2003-166667(2003), the electromagnetic control valve for a variable capacitycompressor to be employed in air conditioners for vehicle for example isconstituted by an assembled body comprising a stator made of a magneticmetallic material, a guide pipe for use as a plunger guide which isfixedly coupled to an lower end portion of the stator and made of anon-magnetic metallic material, a holder fixedly coupled to an lower endportion of the guide pipe and made of a metallic material, and a housingfixedly coupled to the holder and made of a metallic material.

The manufacture of the electromagnetic control valve constituted by theaforementioned assembled body has been conventionally executed asfollows for example. Namely, as shown in FIG. 5(A), a stator 33 isformed into a cylindrical body having a step portion, thereby creating alower end portion having a smaller outer diameter. Then, a guide pipe 35is formed into a cylindrical body having an inner diameter which islarge enough to enable the guide pipe 35 to externally fit on thediametrally contracted portion (i.e. the lower end portion) 33 a of thestator 33 such that an upper edge 35 c of the guide pipe 35 can bebutted against the annular terrace surface 33 c of stator 33. Then, abrazing material 95 is interposed between the terrace surface 33 c ofstator 33 and the upper edge 35 c of the guide pipe 35. Thereafter, thestator 33 and the guide pipe 35 are heated up to a predeterminedtemperature (brazing temperature) in a furnace, thereby brazing thestator 33 to the guide pipe 35. In this case, as shown in FIG. 5(B),since the brazing material 95 is caused to melt in the furnace, thefused brazing material 95 is permitted to flow into a space “Sa” of thefitted portion between the stator 33 and the guide pipe 35. As a result,the stator 33 is caused to move downward. Subsequently, when the fittedportion between the stator 33 and the guide pipe 35 is cooledsufficiently, the stator 33 and the guide pipe 35 are fixedly coupled toeach other through the brazing of the fitted portion (brazing portion“Ja”).

Generally, the compressor to be employed in air conditioners for vehicleis driven by means of the engine, whose rotational speed is designed tobe fluctuated depending on circumstances. Because of this, a variablecapacity compressor which is capable of adjusting the discharge volumeof cooling medium irrespective of the rotational speed of engine isgenerally employed as a compressor for the air conditioner of vehicle.

A control valve to be employed in this compressor for the airconditioners of vehicle is generally constructed as follows. Namely, acooling medium exhibiting a discharge pressure “Pb” is permitted toenter into the crank chamber of compressor from the discharge chamber ofcompressor so as to adjust the pressure “Pc” inside the crank chamber.In this case, the flow rate of cooling medium exhibiting a dischargepressure “Pb” to the crank chamber is restricted such that the quantityof supply (throttling volume) of cooling medium to the crank chamber canbe controlled depending on the sucking pressure “Ps” of compressor. Forthis purpose, various proposals have been suggested or put intopractice, as seen from JP Patent Laid-open Publication (Kokai) No.2002-303262 (2002), where an electromagnetic actuator (solenoid) isemployed.

Further, as for the variable capacity compressor to be employed in airconditioners for vehicle, there are also known a crutch-attachedcompressor wherein the transmission of rotating driving force from theengine to the rotating axis of compressor is effected by means of acrutch, and a crutch-less compressor wherein the rotating driving forceof the engine is directly transmitted to the rotating axis of compressorwithout intervention of a crutch.

The conventional method of manufacturing an electromagnetic controlvalve as described above is accompanied with the following problems.

(i) Since it requires the coupling and fixing work between the guidepipe 35 and the holder as well as between the holder and the housing inaddition to the brazing work between the stator 33 and the guide pipe35, a great deal of troublesome work and time are needed for assemblingthese assembled bodies, thus inevitably increasing the manufacturingcost of the electromagnetic control valve. Further, the assembled bodythat has been once subjected to brazing process can no longer besubjected, as a matter of fact, to a heat treatment after the assemblingthereof. Therefore, there is a problem that when the assembled bodyincludes a magnetic material, the magnetic property of the magneticmaterial cannot be sufficiently enhanced.

(ii) Since the stator 33 and the guide pipe 35 are brazed togetherthrough the employment of brazing material 95 disposed between theterrace surface 33 c of stator 33 and the upper edge 35 c of the guidepipe 35, the brazing material 95 is caused to melt during the step ofbrazing, the fused brazing material 95 is permitted to flow into a space“Sa” of the fitted portion between the stator 33 and the guide pipe 35,causing the stator 33 to move downward as shown in FIG. 5(B). However,there are problems, as the stator 33 is caused to move downward, thatthe stator 33 tends to incline, and that the brazing material 95 ispermitted to leave between the terrace surface 33 c of stator 33 and theupper edge 35 c of the guide pipe 35, thereby preventing the stator 33from sufficiently descending. As a result, the terrace surface 33 c isprevented from butting against the upper edge 35 c of the guide pipe 35,leaving an air gap “β” between the terrace surface 33 c and the upperedge 35 c of the guide pipe 35 even after the brazing. If the air gap“β” is left remained in this manner, the length of air gap between thesucking member to be secured to a lower end of the stator and theplunger becomes inappropriate, thus raising the problem that the controlof flow rate cannot be appropriately performed.

Further, in the case of the control valve for a variable capacitycompressor, especially the control valve for a crutch-less compressor,which is provided with an electromagnetic actuator (solenoid)constituted by a coil, a sucking member, a plunger, etc., when the valueof current to be fed to the coil of electromagnetic actuator (solenoid)becomes zero (OFF of electric current) or nearly zero, the sucking forceof plunger by means of the sucking member is caused to decrease, therebycausing the valve rod (the main body of valve) to shift, in a stroke, tothe maximum lift position due to the valve-opening force of valvespring. As a result, the valve aperture with which the valve body isretractively contacted is caused to completely open (the opening degreeof valve or the magnitude of valve lift becomes maximum). As a result,the flow rate of a cooling medium to be fed from the cooling mediumoutlet port located on the downstream side of the valve aperture to thecrank chamber of compressor is caused to increase in a stroke (maximumflow rate), thus quickly increasing the pressure “Pc” inside the crankchamber of compressor. Namely, the region where the value of current isnearly zero would be turned into an uncontrollable region.

Even if this uncontrollable region is permitted to exist in this manner,almost no problem would be raised in the case of the crutch-lesscompressor. In the case of the crutch-attached compressor however, whenthe control valve is caused to bring into the uncontrollable region, thepressure “Pc” inside the crank chamber exceeds over an allowablelimitation, thereby raising problems in terms of control as well as instructural viewpoints. Thus, the control valve for use in thecrutch-less compressor cannot be utilized as it is in thecrutch-attached compressor.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in view of the circumstancesmentioned above and, therefore, an object of the present invention toprovide a brazing method which makes it possible to rationally performnot only the brazing between a metal member such as a stator made of amagnetic material and a metal member such as a guide pipe made of anon-magnetic material but also the magnetic annealing of these metalmembers. Another object of the present invention is to provide a methodof rationally and precisely manufacture an electromagnetic control valveprovided with an assembled body comprising a stator, a guide pipe, aholder and a housing at low costs.

A further object of the present invention is to provide a control valvefor a variable capacity compressor which can be employed in acrutch-attached compressor and which is capable of controlling the flowrate of cooling medium to be delivered from the cooling medium outletport disposed on a downstream side of valve aperture to the crankchamber of compressor, thereby enabling the flow rate of cooling mediumto be controlled so as not to exceed over an acceptable limit.

With a view to achieving the aforementioned objects, there is provided,according to one aspect of the present invention, a method ofmanufacturing an assembled body composed of a plurality of membersincluding a metal member “A” made of a magnetic material and a metalmember “B” made of a non-magnetic material, the method comprising thesteps of: heating the metal member “A” and the metal member “B” underconditions suitable for magnetic annealing of the metal member “A” tobraze the metal member “A” to the metal member “B” to obtain anassembled body comprising the metal member “A” and the metal member “B”;and gradually cooling the assembled body to perform magnetic annealingof the metal member “A”.

In this case, preferably, the metal member “A” is brazed to the metalmember “B” by making use of a brazing material having a melting pointwhich is lower than a magnetic annealing temperature of the metal member“A”.

In a preferable embodiment, the metal member “A” is formed by making useof a magnetic steel such as an electromagnetic stainless steel, themetal member “B” is formed by making use of a non-magnetic steelmaterial such as non-magnetic stainless steel, and the brazing materialis formed by making use of copper wax or bronze wax.

In another preferable embodiment, the metal member “A” is formed of astep-attached columnar or cylindrical body having a diametrallycontracted end portion and a terrace surface, the metal member “B” isformed of a cylindrical body having an inner diameter which is largeenough to enable it to externally fit on the diametrally contracted endportion, the diametrally contracted end portion of the metal member “A”is provided, at an extended end portion thereof which is remote from theterrace surface, with an annular groove facing an inner peripheralsurface of the metal member “B” for holding a brazing material therein,and the brazing is performed under conditions wherein the metal member“B” is externally fitted on the diametrally contracted end portion withan fitted end of the metal member “B” being butted against the terracesurface and the brazing material being held between the annular grooveand the inner peripheral surface of the metal member “B”.

In a more specific embodiment, the metal member “A” is a stator of anelectromagnetic control valve, and the metal member “B” is a guide pipeto be used as a plunger guide of the electromagnetic control valve.

Further, according to another aspect of the present invention, there isalso provided a method for manufacturing an electromagnetic controlvalve which is composed of an assembled body comprising a stator made ofa magnetic metallic material, a guide pipe for use as a plunger guidewhich is fixedly coupled to an lower end portion of the stator and madeof a non-magnetic metallic material, a holder fixedly coupled to anlower end portion of the guide pipe and made of a metallic material, anda housing fixedly coupled to the holder and made of a magnetic metallicmaterial. In this manufacturing method, the stator is formed of astep-attached columnar or cylindrical body having a diametrallycontracted end portion and a terrace surface, the guide pipe is formedof a cylindrical body having an inner diameter which is large enough toenable it to externally fit on the diametrally contracted end portion,the diametrally contracted end portion of the stator is provided, at anextended end portion thereof which is remote from the terrace surface,with an annular groove facing an inner peripheral surface of the guidepipe for holding a brazing material therein, the guide pipe isexternally fitted on the diametrally contracted end portion with anfitted end of the guide pipe being butted against the terrace surface tothereby temporarily interconnect the stator, the guide pipe, the holderand the housing, and the brazing material is held between the annulargroove and the inner peripheral surface of the guide pipe.

Then, the electromagnetic control valve is subjected to a treatmentwhich comprises the steps of heating the temporarily interconnectedassembled body under conditions for effecting magnetic annealing of themagnetic metallic material such as the stator in a furnace to braze thestator to the guide pipe; and gradually cooling the assembled body afterthe assembled body is taken out of the furnace to perform magneticannealing of the stator, the holder and the housing.

In a preferable embodiment of the aforementioned manufacturing method ofelectromagnetic control valve, the housing is fabricated into aconfiguration enabling the housing to be press-inserted into the holder,the holder and housing are subjected to nickel plating or chromeplating, and the plated housing is press-inserted into the holder,thereby fabricating the temporarily interconnected assembled body.

In a further preferable embodiment of the aforementioned manufacturingmethod of electromagnetic control valve, the holder is formed into astep-attached cylindrical body to thereby enable the guide pipe to besnugly inserted therein, and the fabrication of the temporarilyinterconnected assembled body is performed by inserting the guide pipeinto the holder and, at the same time, by disposing the brazing materialat an interface between the inserted portion of the guide pipe and theholder.

Furthermore, in order to achieve the aforementioned object, the presentinvention provides a control valve for a variable capacity compressor,which is designed to be employed in a crutch-attached compressor.Namely, this control valve for a variable capacity compressorfundamentally comprises a valve rod having a valve body; a valve mainbody provided with a valve chamber having a valve aperture with whichthe valve body can be retractivebly contacted, with an inlet port forcooling medium of discharge pressure which is disposed on an upstreamside of the valve aperture, and with a cooling medium outlet port whichis disposed on a downstream side of the valve aperture and communicatedwith a crank chamber of the compressor; an electromagnetic actuator fordriving the valve rod to move in the direction of opening or closing thevalve aperture; and a pressure sensitive moving member for driving thevalve rod to move in the direction of opening or closing the valveaperture in response to a sucking pressure of the compressor.

This control valve for a variable capacity compressor is furthercharacterized in that the cooling medium outlet port is further providedwith a restricting mechanism for restricting a maximum flow rate of thecooling medium to be fed to the crank chamber.

More specifically, the control valve for a variable capacity compressoraccording to the present invention comprises a valve rod having a valvebody; a valve main body provided with a valve chamber having a valveaperture with which the valve body can be retractivebly contacted, withan inlet port for introducing cooling medium of discharge pressure froma compressor, the inlet port being disposed on an upstream side of thevalve aperture, and with a cooling medium outlet port which is disposedon a downstream side of the valve aperture and communicated with a crankchamber of the compressor; an electromagnetic actuator constituted by acoil, a cylindrical stator disposed on the inner peripheral side of thecoil, a sucking member secured to the stator, and a plunger disposedbelow the sucking member and enabled to slide up and down; a pressuresensitive chamber which is formed on the inner peripheral side of thestator and over the sucking member and to which an inlet pressure isintroduced therein from the compressor; a pressure sensitive drivingmember disposed in the pressure-sensitive chamber; and an operating rodinterposed between a pressure sensitive driving member and the plunger.

In this control valve for a variable capacity compressor, the valve bodyis designed to be moved in the valve-closing direction as the plunger ismoved close to the sucking member and in the valve-opening direction asthe operating rod is pushed downward by the actuation of the pressuresensitive driving member; and the cooling medium outlet port is furtherprovided with a restricting mechanism for restricting a maximum flowrate of the cooling medium to be fed to the crank chamber.

In a preferable embodiment, the restricting mechanism is constituted bya restricting pore-attached closing member which is secured to thecooling medium outlet port.

In a further preferable embodiment, the restricting pore-attachedclosing member is provided with one or a plurality of restricting pores,a total area of aperture of the restricting pore-attached closing memberis less than a maximum effective aperture area of the valve aperture.

In a further preferable embodiment of the control valve for a variablecapacity compressor, the restricting mechanism is provided so as toregulate the magnitude of opening of valve in order to inhibit changesin gradient of controlling pressure.

In this case, the magnitude of lift of the valve body from the valveaperture is preferably regulated for regulating the magnitude of openingof valve.

According to the manufacturing method of a control valve for a variablecapacity compressor as proposed by the present invention, a metal member“A” made of a magnetic material is brazed to a metal member “B” made ofa non-magnetic material in such a manner that by making use of a brazingmaterial having a melting point which is lower than a magnetic annealingtemperature of the metal member “A”, the metal member “A” and the metalmember “B” are heated to braze them under conditions suitable formagnetic annealing of the metal member “A” to obtain an assembled bodycomprising the metal member “A” and the metal member “B”, and theassembled body is taken out of the furnace to gradually cool to performmagnetic annealing of the metal member “A”. As a result, it is possibleto satisfactorily perform the magnetic annealing even after the brazing,thereby making it possible to enhance the magnetic property of thebrazed assembled body comprising a magnetic metallic material.

Further, according to the manufacturing method of the electromagneticcontrol valve as set forth by the present invention, an annular groovefor holding a brazing material is provided at an extended end portion(which is remote from the terrace surface) of the diametrally contractedend portion of the stator and the guide pipe is externally fitted on thediametrally contracted end portion with an fitted end of the guide pipebeing butted against the terrace surface to thereby temporarilyinterconnect the stator, the guide pipe, the holder and the housing. Asa result, the brazing material is enabled to be held between the annulargroove and the inner peripheral surface of the guide pipe. Then, thistacked assembled body is heated in a furnace under conditions foreffecting magnetic annealing of the magnetic metallic material such asthe stator to perform the brazing of the stator and the guide pipe.Thereafter, the assembled body is gradually cooled to perform magneticannealing of the stator, the holder and the housing.

In this case, due to a capillary action, the fused brazing material issucked up into an air gap of the fitted portion between the stator andthe guide pipe. In this case, since the upper end of the guide pipe isbutted against the terrace surface of the stator from the beginningwithout the interposition of brazing material therebetween and sincethere is no possibility of the stator being lifted up by the brazingmaterial that has been sucked up into the air gap of the fitted portionbetween the stator and the guide pipe, the contacted state between theupper end of the guide pipe and the terrace surface of the stator can beretained during the brazing process. After finishing the brazing in thismanner, the assembled body is permitted to cool, thereby brazing andfixedly coupling the stator to the guide pipe through the fitted portionthereof. At the same time, the magnetic annealing of the stator, theholder and the housing was achieved and the magnetic properties of theassembled body can be enhanced.

According to the aforementioned manufacturing method, since the brazingmaterial can be prevented from entering into the air gap between theupper end of the guide pipe and the terrace surface of the stator, thecontacted state between the upper end of the guide pipe and the terracesurface of the stator can be retained even after finishing the brazingprocess and hence no air gap can be permitted to generate between theseportions. As a result, the length of air gap between the sucking memberto be secured to a lower end of the stator and the plunger can besecured appropriately, thus making it possible to manufacture anelectromagnetic control valve which is capable of appropriatelyperforming the control of flow rate.

Additionally, since the housing is fabricated into a configurationenabling the housing to be press-inserted into the holder and sincenickel plating or chrome plating is applied to the holder and housing,the resultant plated housing being subsequently press-inserted into theholder to fabricate an assembled body of tacked state, it is possible tobring about a diffusion bonding effect at the plated portions of thesehousing and holder. As a result, the bonding strength between thehousing and the holder can be greatly increased as compared with thatcan be obtained when the housing is simply press-inserted into theholder.

Further, in the case of the control valve for a variable capacitycompressor according to the present invention, even if the valveaperture is completely or nearly completely opened, since the maximumflow rate of the cooling medium to be fed to the crank chamber ofcompressor can be throttled and restricted by a restricting mechanismsuch as a throttle aperture-attached closing member provided at thecooling medium outlet port, it is possible to prevent the maximum flowrate from exceeding over an acceptable limit in the crutch-attachedcompressor. Therefore, the control valve of the present invention can beused in the crutch-attached compressor. Furthermore, since the controlvalve of the present invention can be fabricated by simply attaching arestricting mechanism such as a throttle aperture-attached closingmember to the conventional control valve for a crutch-less compressor,most of parts for control valve can be used not only for the crutch-lesscompressor but also for the crutch-attached compressor when the controlvalves are manufactured for use in a crutch-less compressor or in acrutch-attached compressor, thereby making it possible to reduce themanufacturing cost of the control valve.

Furthermore, according to the control valve of the present invention,since the magnitude of opening of valve (the magnitude of lift from thevalve aperture of valve body) can be regulated through the provision ofthe restricting mechanism so as to suppress the change in gradient ofcontrolling pressure, the gradient of controlling pressure in thecontrollable region can be made almost identical with the gradient ofcontrolling pressure to be obtained in the situation where therestricting mechanism is not provided (i.e. the situation of the controlvalve for use in a crutch-less compressor). Therefore, it is nowpossible not only to restrict the aforementioned maximum flow rate butalso to substantially completely satisfy the controlling characteristicsdemanded of the control valve for use in the crutch-attached compressor.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a longitudinal sectional view illustrating one embodiment ofthe electromagnetic control valve that has been manufactured accordingto the brazing method and manufacturing method representing oneembodiment according to the present invention;

FIG. 2 is a longitudinal sectional view illustrating an assembled bodyprovided with the electromagnetic control valve shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view illustrating the brazedportion of the stator and the guide pipe both disposed in theelectromagnetic control valve shown in FIG. 1;

FIG. 4 is an enlarged cross-sectional view illustrating the brazedportion of the stator and the guide pipe as well as the press-insertedportion of the housing in the holder;

FIGS. 5(A) and 5(B) respectively shows a longitudinal sectional view forexplaining the problems involved in the brazing of the stator and theholder of the conventional electromagnetic control valve;

FIG. 6 is a longitudinal sectional view illustrating a second embodimentof the control valve for a variable capacity type (crutch-attached)compressor according to the present invention;

FIG. 7 is an enlarged cross-sectional view of the region of coolingmedium outlet port (and chamber) for illustrating a third embodiment ofthe control valve for a variable capacity type (crutch-attached)compressor according to the present invention; and

FIG. 8 is a graph illustrating the relationship between the pressure“Pc” and the values of electric current for explaining the operation,action and effects of the control valve of the third embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Next, several embodiments of the brazing method, the manufacturingmethod of electromagnetic control valve, and the electromagnetic controlvalve of the present invention will be explained in detail withreference to the drawings.

First Embodiment

FIG. 1 shows a longitudinal sectional view illustrating one embodimentof the electromagnetic control valve for a variable capacity compressor,that has been manufactured according to the brazing method andmanufacturing method representing one embodiment according to thepresent invention. In the following description, the construction of theelectromagnetic control valve 1 will be explained at first, and then themethod of manufacturing the electromagnetic control valve 1 will beexplained.

The control valve I shown in FIG. 1 is equipped with a valve rod 15having a valve body 1 a; a valve main body 20 composed of a valvechamber 21 provided with a valve seat (valve aperture) 22 with which thevalve body 1 a can be retractivebly contacted, a plurality of inletports 25 for introducing a cooling medium of discharge pressure “Pd”from the compressor into the outer peripheral portion of the valvechamber 21 (on the upstream side of the valve seat 22), and a highpressure cooling medium supply port 26 disposed below (downstream sideof) the valve seat 22 and communicated with the crank chamber ofcompressor; and an electromagnetic actuator 30.

The electromagnetic actuator 30 is equipped with an electromagnetic coil32 having a connector 31 for electroexcitation, a step-attachedcylindrical stator 33 made of a magnetic metallic material and disposedon the inner peripheral side of the electromagnetic coil 32, a suckingmember 34 having U-shaped cross-section and press-inserted into a lowerinner peripheral end portion of the stator 33, a plunger 37 slidablydisposed to move up and down in a guide pipe 35 and located below thesucking member 34, the cylindrical guide pipe 35 fixedly coupled,through a brazing which is applied to an upper inner peripheral end 35a, to a lower outer peripheral end portion (diametrally contracted endportion 33 a) of the stator 33, a step-attached cylindrical housing 60disposed covering the outer peripheral portion of the coil 32, and ashort cylindrical holder 50 interposed between an upper end portion ofthe valve main body 20 and the coil 32.

A lower end portion of the pipe 35 is inserted in a diametrally enlargedportion 50 b of the holder 50 and fixedly coupled thereto by means ofbrazing (as described hereinafter). A lower diametrally contractedportion 61 of the housing 60 is externally inserted over an outerperipheral portion of holder 50 (as described hereinafter). An upper endportion 62 of the housing 60 is calked to nearly an upper end portion ofthe coil 32. At a lower end portion of the holder 50, there isintegrally formed a thin wall flanged cylindrical portion 50 a which isexternally fitted on an upper outer peripheral wall of the valve mainbody 20. The holder 50 is fixed to the valve main body 20 through thepeel-calking work of the cylindrical portion 50 a.

An assembled body 80 of this embodiment is constituted by the stator 33,the guide pipe 35, the holder 50 and the housing 60 all constructed asdescribed above (as described hereinafter with reference to FIGS. 2, 3and 4).

Additionally, a hexagon socket head adjusting screw 65 is screwed on anupper portion of the stator 33. A pressure sensitive chamber 45 intowhich the sucking pressure “Ps” of compressor is to be introduced isformed between the adjusting screw 65 attached to the inner peripheralwall of stator 33 and the sucking member 34. In this pressure sensitivechamber 45, there is disposed, as a pressure sensitive driving member, abellows main body 40 consisting of a bellows 41, a downwardly projectedupper stopper 42, a reverse U-shaped lower stopper 43 and a compressioncoil spring 44. Further, a compression coil spring 46 for urging thebellows main body 40 to contract (in the direction to contract it towardthe adjusting screw 65) is interposed between the bellows main body 40and the sucking member 34. Further, a step-attached operating rod 14piercing through the sucking member 34 is interposed between the reverseU-shaped lower stopper 43 and a U-shaped portion 37 c of plunger 37.Additionally, a valve-opening spring 47 made of a compression coilspring for urging the valve rod 15 downward (in the direction to openthe valve) by way of the plunger 37 is interposed between the suckingmember 34 and the U-shaped portion 37 b of plunger 37.

On the other hand, a reverse U-shaped stopper 28 for regulating thelowermost descending position of the plunger 37 is projected upward overthe valve chamber 21 of the valve main body 20. A guide hole 19 in whichthe valve rod 15 is slidably inserted is formed at a central portion ofthe valve main body 20 including the reverse U-shaped stopper 28 andlocated over the valve chamber. A suction pressure-introducing chamber23 is formed around the outer peripheral wall of the reverse U-shapedstopper 28 and a plurality of suction pressure coolingmedium-introducing ports 27 are formed in the outer wall of the suctionpressure-introducing chamber 23. A cooling medium of sucking pressure“Ps” that has been introduced into the suction pressure-introducingchamber 23 from the cooling medium-introducing ports 27 is designed tobe introduced into the pressure sensitive chamber 45 via longitudinalgrooves 37 a formed on the outer peripheral wall of plunger 37, via athrough-hole 37 d formed at a central axis of plunger 37 and via athrough-hole 39 formed in the sucking member 34.

A valve-closing spring 48 made of a conical compression spring forurging the valve rod 15 upward is disposed at a lower portion (ahigh-pressure cooling medium supply port 26) of the valve main body 20.By the effect of urging force of this valve-closing spring 48, an upperend portion of the valve rod 15 is always brought into press-contactwith the through-hole 37 d portion of plunger 37.

In the control valve 1 constructed as described above, when the solenoidportion consisting of the coil 32, the stator 33 and the sucking member34 is electroexcited, the plunger 37 is drawn toward the sucking member34, forcing the valve rod 15 to move upward (in the valve-closingdirection) by the urging force of the valve-closing spring 48. On theother hand, the cooling medium of suction pressure “Ps” that has beenintroduced into the cooling medium-introducing ports 27 from thecompressor is introduced from the suction pressure-introducing chamber23 into the pressure sensitive chamber 45 via longitudinal grooves 37 aformed on the outer peripheral wall of plunger 37 and via a through-hole39 formed in the sucking member 34. The bellows main body 40 (theinterior thereof is kept in vacuum) is caused to displace, i.e. contractor expand depending on the pressure (the suction pressure “Ps”) insidethe pressure sensitive chamber 45 (when the suction pressure “Ps” ishigh, the bellows main body 40 is contracted, and when the suctionpressure “Ps” is low, the bellows main body 40 is expanded). Then, thisdisplacement is transmitted, via the operating rod 14 and the plunger37, to the valve rod 15, thereby making it possible to adjust themagnitude of opening of valve (the effective cross-sectional area ofpassageway). Namely, the magnitude of opening of valve can be determineddepending on the sucking force of the plunger 37 to be effected by thesolenoid portion consisting of the coil 32, the stator 33 and thesucking member 34, on the urging force of the bellows main body 40, andon the urging force of the valve-opening spring 47 and the valve-closingspring 48. Further, depending on this magnitude of opening of valve, thequantity (magnitude of restriction) of cooling medium of dischargepressure “Pd” that has been introduced from the discharge pressurecooling medium inlet port into the valve chamber 21 and that can bedelivered toward the supply port 26, i.e. toward the crank chamber canbe adjusted, thus making it possible to control the pressure “Pc” insidethe crank chamber.

The control valve 1 of this embodiment which is constructed as describedabove can be manufactured as follows. As shown in FIGS. 2 and 3, thestator 33 is formed into a step-attached cylindrical body having adiametrally contracted end portion 33 a and a terrace surface 33 c. Theguide pipe 35 is formed into a cylindrical body having an inner diameterwhich is large enough to enable an upper inner peripheral end portion 35a to externally fit on the diametrally contracted end portion 33 a(upper end portion 35 c of guide pipe 35 is tapered). An annular groove33 d having a semicircular cross-section for holding a brazing material90 therein is formed at an extended end portion (which is remote fromthe terrace surface 33 c) of the diametrally contracted end portion 33 aof the stator 33. Then, the upper inner peripheral end portion 35 a ofthe guide pipe 35 is externally fitted on the diametrally contracted endportion 33 a with an upper end 35 c of the guide pipe 35 being buttedagainst the terrace surface 33 c to thereby hold the brazing material 90between the groove 33 d and the inner peripheral surface of the guidepipe 35, thereby preventing the brazing material 90 from falling off.

In this case, a magnetic steel (the temperature of magnetic annealing:1100-1150° C.) such as electromagnetic stainless steel is employed as amaterial for the stator 33. A non-magnetic steel such asnon-electromagnetic stainless steel (for example, SUS305) is employed asa material for the guide pipe 35. Copper wax (melting temperature: 1083°C.) or bronze wax (melting temperature: 880-1025° C.) for stainlesssteel or general steel is employed as a material for the brazingmaterial 90. By the way, as for the material for the stator 33, althoughstainless steel is employed herein in view of preventing the generationof rust, it is also possible to employ other kinds of steel material.

Alternatively, as shown in FIG. 4, the lower diametrally contractedportion 61 of the housing 60 may be constructed into such a size and aconfiguration that it can be externally inserted with pressure over anouter peripheral portion (diametrally contracted portion 50 f) of holder50. At the same time, nickel plating or chrome plating is applied to theholder 50 and the housing 60, and the lower diametrally contractedportion 61 of housing 60 thus plated is press-inserted into thediametrally contracted portion 50 f of holder 50 until the lower end 61d of diametrally contracted portion 61 is butted against the terracesurface 50 d of holder 50. Herein, as for the material for the housing60, steel for drawing work (SPCE) is employed and as for the materialfor the holder 50, steel such as free cutting sulfur steel is employed.By the way, as for the plating, chrome plating may be employed in placeof the nickel plating.

Alternatively, the holder 50 may be formed into a step-attachedcylindrical body having a terrace surface 50 c and a diametrallyenlarged portion 50 b to thereby enable the guide pipe 35 to be snuglyinserted therein. Then, a lower end portion 35 b of the guide pipe 35 isinserted into the diametrally enlarged portion 50 b of holder 50 untilthe lower end 35 e thereof is butted against the terrace surface 50 c ofthe holder 50. At the same time, a brazing material 92 (the samematerial as that of brazing material 90) is mounted on a portion of theholder 50 (a chamfered portion 50 r formed at an upper inner peripheraledge of the holder 50) which is designed to be engaged with the guidepipe.

In this manner, the stator 33, the guide pipe 35, the holder 50 and thehousing 60 constituting the assembled body 80 are temporarilyinterconnected with each other. Then, the assembled body 80′ in astacked state (a state shown in FIG. 2) is heated at a predeterminedtemperature by making use of a continuous heat treating furnace equippedwith a work-transferring means such as a mesh belt conveyer. Morespecifically, this heat treating furnace is provided with a heatingsection and a cooling section located contiguous to the heating section.The assembled body 80′ tacked as described above is placed, in anerected state (the state shown in FIG. 2), on a conveyer andcontinuously or intermittently transferred into the treating furnace, inwhich the assembled body 80′ is heated, while being kept moving in thetreating furnace, at the aforementioned magnetic annealing temperaturefor a predetermined period of time (for example, about one hour).Thereafter, the assembled body 80′ is delivered to the cooling sectionto cool the assembled body 80′. In this case, the atmosphere inside thefurnace should preferably be a reducing atmosphere (a suitable quantityof reducing gas such as hydrogen gas is added to an inert gas such asnitrogen gas) in order to prevent the oxidation of the assembled body80′.

When the assembled body 80′ is heated in this manner in the treatingfurnace, the brazing between the stator 33 and the guide pipe 35 as wellas between the guide pipe 35 and the holder 50 can be executed. When theassembled body 80′ is subsequently cooled, the magnetic annealing of thestator 33, the holder 50 and housing 60 can be executed. In this case,at the brazed portion between the stator 33 and the guide pipe 35, thebrazing material 90 is fused and, due to capillary action, the fusedbrazing material 90 is sucked up through the air gap “S” formed at thefitted portion between the diametrally contracted portion 33 a of stator33 and the guide pipe 35 as shown in FIG. 3. In this case, since theterrace surface 33 c of stator 33 is butted against the upper end 35 cof the guide pipe 35 from the beginning and hence the brazing materialis not permitted to exist between the terrace surface 33 c and the upperend 35 c of the guide pipe 35 and, furthermore, since the stator 33 isprevented from being lifted upward by the brazing material 90 that hasbeen sucked up into the space “Sa” of fitted portion between the stator33 and the guide pipe 35, the terrace surface 33 c of stator 33 can bekept directly contacted with the upper end 35 c of the guide pipe 35even during the brazing process. In the assembled body 80 assembled inthis manner, the stator 33 and the guide pipe 35 can be brazed andfixedly coupled to each other at the fitted portion thereof during asingle step of brazing and, at the same time, the magnetic annealing ofthe magnetic metallic materials of the stator 33, the holder 50 and thehousing 60 is effected, thus sufficiently improving the magneticproperties thereof.

Further, since the stator 33 and the guide pipe 35 are brazed to eachother while retaining the initial state where the terrace surface 33 cof stator 33 is butted against the upper end 35 c of the guide pipe 35,there is no possibility that the air gap (β in FIG. 5(B)) as seen in theconventional method can be generated. As a result, the length of air gapbetween the sucking member 34 to be secured to a lower end of the stator35 and the plunger 37 can be secured appropriately, thus making itpossible to manufacture an electromagnetic control valve which iscapable of appropriately performing the control of flow rate.

Additionally, at the brazed portion between the lower end portion 35 bof the guide pipe 35 and the holder 50, the brazing material 92 is fusedand the fused brazing material 92 is permitted to flow into the air gap“Sb” formed at the fitted portion between the lower end 35 b of guidepipe 35 and the diametrally enlarged portion 50 b of the holder 50. Aredundant portion of the brazing material 92 is accumulated at a storageportion 50 g. Thereafter, when the brazed portion is cooled, the guidepipe 35 and the holder 50 are fixedly coupled to each other through thebrazing of the fitted portion thereof (brazed portion Jb).

As described above, according to this embodiment, the brazing betweenthe stator 33 and the guide pipe 35 as well as between the guide pipe 35and the holder 50 can be executed simultaneous with the magneticannealing of the stator 33, the holder 50 and housing 60 during a singlebrazing process.

Furthermore, since the housing 60 is fabricated into a configurationenabling the housing 60 to be press-inserted into the holder 50 andsince nickel plating or chrome plating is applied to the holder 50 andhousing 60, the resultant plated housing 60 being subsequentlypress-inserted into the holder 50 to fabricate an assembled body 80′ oftacked state, it is possible to bring about a diffusion bonding effectat the plated portions of these housing 60 and holder 50. As a result,the bonding strength between the housing 60 and the holder 50 can begreatly increased as compared with that can be obtained when the housing60 is simply press-inserted into the holder 50. In this manner, thebonding strength can be sufficiently enhanced by simply performing theplating and the press-insertion as described above. In this case also,since the heat treatment for obtaining the diffusion bonding effect canbe executed during a single brazing process, a total time for heattreatment can be shortened as compared with the case where the heattreatment and the brazing are separately performed, thus making itpossible to further reduce the cost for heat treatment as well as themanufacturing cost.

Further, since the coupling between the stator 33 and the guide pipe 35as well as the coupling between the guide pipe 35 and the holder 50 canbe respectively performed through the brazing and press-insertion,fixing members such as O-ring is no longer required to be employed, thusmaking it possible to reduce the number of parts and to enhance theassembling property and fabricating property, thus making it possible tofurther reduce the manufacturing cost.

Next, another embodiment of control valve for compressor according tothe present invention will be explained in detail with reference to thedrawings.

Second Embodiment

FIG. 6 is a longitudinal sectional view illustrating a second embodimentof the control valve for a variable capacity type (crutch-attached)compressor according to the present invention.

The control valve 1′ for crutch-attached compressor shown in FIG. 6 isconstructed such that a restricting mechanism (throttleaperture-attached closing member 70) to be described hereinafter isattached to a control valve for a crutch-less compressor. In otherwords, all of the components other than the restricting mechanism arethe same as those of the crutch-less compressor. Next, the constructionof the control valve 1′ will be explained in detail as follows.

The control valve 1′ comprises: a valve rod 15 having a valve body 15 ahaving a +-shaped or T-shaped cross-section and attached to a lower endof the valve rod 15; a valve main body 20 provided with a valve chamber21 having a valve aperture (valve seat) 22 with which the valve body 15a can be retractivebly contacted, with a plurality of inlet ports 25 forintroducing cooling medium of discharge pressure “Pd” from a compressor,the inlet ports 25 being formed in an outer peripheral portion of thevalve chamber 21 (i.e. the inlet ports 25 being disposed on an upstreamside of the valve aperture 22), and with a cooling medium outlet port 26which is disposed below (on a downstream side of) the valve aperture 22and communicated with a crank chamber of the compressor; and anelectromagnetic actuator 30.

This electromagnetic actuator 30 is equipped with a coil 32 having aconnector 31 for electroexcitation, a cylindrical stator 33 disposed onthe inner peripheral side of the coil 32, a sucking member 34 havingU-shaped cross-section and press-inserted into a lower inner peripheralend portion of the stator 33, a flange 35 a-attached pipe 35 welded,through an upper end thereof, to a lower outer peripheral end portion(step portion) of the stator 33; a plunger 37 slidably disposed to moveup and down inside the pipe 35 and located below the sucking member 34,and a closed end aperture-attached cylindrical housing 60 disposedcovering the outer peripheral portion of the coil 32.

Further, a hexagon socket head adjusting screw 65 is screwed on an upperportion of the stator 33. A pressure sensitive chamber 45 into which thesucking pressure “Ps” of compressor is to be introduced is formedbetween the adjusting screw 65 attached to the inner peripheral wall ofstator 33 and the sucking member 34. In this pressure sensitive chamber45, there is disposed, as a pressure sensitive driving member, a bellowsmain body 40 consisting of a bellows 41, a downwardly projected upperstopper 42, a reverse U-shaped lower stopper 43 and a compression coilspring 44. Further, a compression coil spring 46 for urging the bellowsmain body 40 to contract (in the direction to contract it toward theadjusting screw 65) is interposed between the bellows main body 40 andthe sucking member 34. Further, a step-attached operating rod 14piercing through the sucking member 34 is interposed between the reverseU-shaped lower stopper 43 and a U-shaped portion 37 c of plunger 37.Additionally, a valve-opening spring 47 made of a compression coilspring for urging the valve rod 15 downward (in the direction to openthe valve) by way of the plunger 37 is interposed between the suckingmember 34 and the U-shaped portion 37 c of plunger 37.

On the other hand, a reverse U-shaped stopper 28 for regulating thelowermost descending position of the plunger 37 is projected upward overthe valve chamber 21 of the valve main body 20. A guide hole 19 in whichthe valve rod 15 is slidably inserted is formed at a central portion ofthe valve main body 20 including the reverse U-shaped stopper 28 andlocated over the valve chamber. A suction pressure-introducing chamber23 is formed around the outer peripheral wall of the reverse U-shapedstopper 28 and a plurality of suction pressure coolingmedium-introducing ports 27 are formed in the outer wall of the suctionpressure-introducing chamber 23. A cooling medium of sucking pressure“Ps” that has been introduced into the suction pressure-introducingchamber 23 from the cooling medium-introducing ports 27 is designed tobe introduced into the pressure sensitive chamber 45 via longitudinalgrooves 37 a formed on the outer peripheral wall of plunger 37, via athrough-hole 37 d formed at a central axis of plunger 37 and via athrough-hole 39 formed in the sucking member 34.

A valve-closing spring 48 made of a conical compression spring forurging the valve rod 15 upward to push the through-hole 37 d portion ofplunger 37 through an upper end of the valve rod 15 is disposed in thecooling medium outlet port 26 provided at a lowermost portion of thevalve main body 20.

The lower flange portion 35 a of the pipe 35 is mounted, through anO-ring 57, on an upper end of the valve main body 20. a flange 56a-attached short cylindrical pipe holder 56 is interposed between theflange portion 35 a and the coil 32. These flange portions 35 a and 56 aare both fixed by means of the upper outer peripheral chamfering portion29 of the valve main body 20. An open bottom portion 61 of the housing60 is press-inserted in an upper end portion of the pipe holder 56. Anupper end portion of the housing 60 is calked to the flange portion 31 cof the connector 31. An O-ring 66 is interposed between the housing 60and the connector 31. By the way, at a lower central portion of theconnector 31, there is formed a recessed portion 31 a in which aprojected portion 31 b to be engaged with the hexagonal hole of theadjusting screw 65 is formed. An upper portion of the stator 33 as wellas an upper portion of the adjusting screw 65 is inserted into thisrecessed portion 31 a.

An annular anchoring groove 75 having a calking portion 76 is formed ona lower inner peripheral portion of the cooling medium outlet port 26which is provided at a lowermost portion of the valve main body 20. Inthis anchoring groove 75, a restricting hole-attached closing member 70acting as a restricting mechanism is hermetically mounted and calked,thereby making this cooling medium outlet port 26 into a restrictinghole-attached closed chamber. The restricting hole-attached closingmember 70 has a thick disk at a central portion thereof and afunnel-shaped restricting through-hole 71 at a central portion thereof.The opening area of this restricting through-hole 71 is made smallerthan a maximum effective opening area (fully opened state) of the valveaperture 22 which is designed to be opened or closed by the valve body15 a of valve rod 15. Namely, the opening area of this restrictingthrough-hole 71 is set to such a size that the maximum flow rate ofcooling medium to be fed from the cooling medium outlet port (chamber)to the crank chamber of the crutch-attached compressor can be restrictedso as not to exceed over an acceptable limit (a limitation to preventany trouble in the operation of crutch-attached compressor). By the way,a peripheral portion outside the central thick portion of therestricting hole-attached closing member 70 is formed into a spring shoefor receiving a lower end portion of the valve-closing spring 48.

In the control valve 1′ constructed as described above, when thesolenoid portion consisting of the coil 32, the stator 33 and thesucking member 34 is electroexcited, the plunger 37 is drawn toward thesucking member 34, forcing the valve rod 15 to move upward (in thevalve-closing direction) by the urging force of the valve-closing spring48. On the other hand, the cooling medium of suction pressure “Ps” thathas been introduced into the cooling medium-introducing ports 27 fromthe compressor is introduced from the suction pressure-introducingchamber 23 into the pressure sensitive chamber 45 via longitudinalgrooves 37 a formed on the outer peripheral wall of plunger 37 and via athrough-hole 39 formed in the sucking member 34. The bellows main body40 (the interior thereof is kept in vacuum) is caused to displace, i.e.contract or expand depending on the pressure (the suction pressure “Ps”)inside the pressure sensitive chamber 45 (when the suction pressure “Ps”is high, the bellows main body 40 is contracted, and when the suctionpressure “Ps” is low, the bellows main body 40 is expanded). Then, thisdisplacement is transmitted, via the operating rod 14 and the plunger37, to the valve rod 15, thereby making it possible to adjust themagnitude of opening of valve (the magnitude of lift from the valveaperture 22 of the valve body 15 a), in other words, the flow rate ofcooling medium to be delivered from the valve aperture 22. Namely, theflow rate of cooling medium can be determined depending on the suckingforce of the plunger 37 to be effected by the solenoid portionconsisting of the coil 32, the stator 33 and the sucking member 34, onthe urging force of the bellows main body 40, and on the urging force ofthe valve-opening spring 47 and the valve-closing spring 48.

In the case, if it is assumed that the restricting hole-attached closingmember 70 is not existed or the opening area of the restrictingthrough-hole 71 is sufficiently large, in other words, if the controlvalve 1′ is a control valve for use in a crutch-less compressor, themagnitude of opening of valve (the magnitude of lift from the valveaperture 22 of the valve body 15 a) relative to the value of electriccurrent to be fed to the coil 32 is permitted to continuously (linearly)change as the value of electric current changes from small to large.However, when the value of electric current becomes zero or nearly zero,the sucking force of the plunger 37 by the sucking member 34 becomessmaller, so that the valve rod 15 is pushed down, in a stroke, to themaximum descending position (maximum lift position) due to thevalve-opening force of valve-opening spring 47, thereby fully openingthe valve aperture 22 (the magnitude of opening becomes maximum). As aresult, the flow rate of a cooling medium to be fed from the coolingmedium outlet port 26 located on the downstream side of the valveaperture 22 to the crank chamber of compressor is caused to increase ina stroke (maximum flow rate), thus quickly increasing the pressure “Pc”inside the crank chamber of compressor.

Namely, the region where the value of electric current is nearly zerowould be turned into an uncontrollable region. Even if thisuncontrollable region is permitted to exist in this manner, almost noproblem would be raised in the case of the crutch-less compressor. Inthe case of the crutch-attached compressor however, when the controlvalve is caused to bring into the uncontrollable region, the pressure“Pc” inside the crank chamber exceeds over an allowable limitation,thereby raising problems in terms of control as well as in structuralviewpoints.

Whereas in the case of the control valve 1′ according to thisembodiment, since the closing member 70 equipped with the restrictingthrough-hole 71 having a predetermined opening area is attached to thecooling medium outlet port 26, even if the valve aperture 22 is fullyopened or nearly fully opened, the maximum flow rate of cooling mediumto be fed to the crank chamber of compressor can be restricted by therestricting through-hole 71 so as not to exceed over an acceptable limitregulated in the crutch-attached compressor. In this case, when thevalue of electric current to be fed to the coil 32 becomes zero ornearly zero, the valve rod 15 is pushed downward by the valve-openingforce of the valve-opening spring 47 as described above. In this casehowever, since the flow rate of cooling medium to be fed to the crankchamber of compressor can be restricted by the restricting through-hole71, the pressure inside the cooling medium outlet port (chamber) isincreased, thereby rendering the descending rate of the valve rod 15(valve body 15 a) to become moderate, thus preventing the flow rate ofcooling medium passing through the valve aperture 22 from quicklyincreasing.

As described above, in the case of the control valve 1′ according tothis embodiment, even if the valve aperture 22 is fully opened or nearlyfully opened, the maximum flow rate of cooling medium to be fed to thecrank chamber of compressor can be restricted by the restrictingthrough-hole 71 so as not to exceed over an acceptable limit regulatedin the crutch-attached compressor. Therefore, the control valve 1′ wouldbe suited for use in a crutch-attached compressor, and moreover since itis only required to attach a restricting mechanism such as therestricting hole-attached closing member 70 to the control valve of thecrutch-less compressor, most of parts for the control valve can be usednot only for the crutch-less compressor but also for the crutch-attachedcompressor when the control valves are manufactured for use in acrutch-less compressor or in a crutch-attached compressor, therebymaking it possible to reduce the manufacturing cost of the controlvalve.

Third Embodiment

Next, a third embodiment of the control valve for a variable capacitytype (crutch-attached) compressor according to the present inventionwill be explained.

The control valve 1″ according to this embodiment is the same infundamental structure as that of the control valve 1′ of the secondembodiment shown in FIG. 6 except that the magnitude of opening of valve(the magnitude of lift “L” from the valve aperture 22 of the valve body15 a (see FIG. 7)) is regulated in order to suppress the change ingradient of controlling pressure (see FIG. 8) that may be caused due tothe provision of the throttle aperture-attached closing member 70 as arestricting mechanism.

Next, the construction of the control valve 1″ will be explained indetail as follows.

Due to the provision of the throttle aperture-attached closing member 70as a restricting mechanism, when the value of electric current to be fedto the coil 32 becomes smaller than “Ia” which is close to zero (forexample, 0.1A) (thus entering into uncontrollable region), the magnitudeof opening of valve (magnitude of lift “L”) becomes the maximum ornearly maximum. However since the maximum flow rate of cooling medium tobe fed to the crank chamber of compressor is restricted by therestricting through-hole 71 of the closing member 70, the pressure “Pc”to be fed to the crank chamber of compressor is almost the same as thepressure value “Qa” on the occasion where the value of electric currentis “Ia”.

Whereas in the controllable region where the value of electric currentto be fed to the coil 32 is not less than “Ia” (for example, 0.1A), asthe value of electric current to be fed to the coil 32 changes fromsmall to large, the pressure “Pc” becomes smaller and the gradient ofcontrolling pressure becomes θ′.

However, the gradient of controlling pressure demanded in the controlvalve for crutch-attached compressor is θ(θ>θ′) as shown in FIG. 3 by asolid line. This controlling pressure gradient θ is equal to thecontrolling pressure gradient in the controllable region in the casewhere a restricting mechanism (throttle aperture-attached closing member70) is not provided, i.e. under the condition where the control valvefor a crutch-less compressor is employed. Thus, the controlling pressuregradient θ′ of the situation where a restricting mechanism is providedis smaller than the controlling pressure gradient θ of the situationwhere a restricting mechanism is not provided. Therefore, thecontrollable range (D′) of the pressure “Pc” where a restrictingmechanism is provided becomes narrower than that (D) of the pressure“Pc” where a restricting mechanism is provided.

The reason for causing the controlling pressure gradient to becomesmaller (θ−>θ′) due to the provision of the restricting mechanism isassumed to be ascribed to the accumulation of pressure (increase ofpressure) in the cooling medium outlet port (chamber) 26 due to theexistence of the restricting mechanism (throttle aperture-attachedclosing member 70). In this case, this trend becomes more conspicuous asa difference between the magnitude of opening of valve (magnitude oflift “L”) and the diameter Φ of the restricting through-hole 71 ofthrottle aperture-attached closing member 70 (opening area=magnitude ofrestriction) becomes larger. Furthermore, when the pressure isaccumulated in the cooling medium outlet port (chamber) 26, the forcefor closing the valve body 15 a (valve-closing force) is also caused toincrease.

Therefore, in this embodiment, the diameter Φ of the restrictingthrough-hole 71 of throttle aperture-attached closing member 70 (openingarea=magnitude of restriction) is selected such that it would not badlyaffect the valve opening/closing movement and, at the same time, themagnitude of opening of valve (magnitude of lift “L”) is regulated, morespecifically, the magnitude of opening of valve (magnitude of lift “L”)is regulated so as to make it smaller than that of the aforementionedsecond embodiment, thereby further restricting the flow rate of coolingmedium to be delivered from the valve chamber 21 to the cooling mediumoutlet port (chamber) 26 through the valve aperture 22 as compared withthe flow rate of cooling medium set forth in the aforementioned secondembodiment.

More specifically, the diameter Φ of the restricting through-hole 71 ofthrottle aperture-attached closing member 70 is confined within therange of 1.2-1.3 mm, thus regulating the maximum lift “L” to the rangeof 0.15-0.25 mm. By the way, in the second embodiment, the bore diameterΦ is set to 4.9 mm for example and the maximum lift “L” is set 0.65 mmfor example.

In the case of the control valve 1″ for a variable capacity compressoraccording to the third embodiment constructed in this manner, since themagnitude of lift “L” can be regulated through the provision of therestricting mechanism (throttle aperture-attached closing member 70) soas to suppress the change in gradient of controlling pressure, thegradient of controlling pressure in the controllable region can be madealmost identical with the gradient θ (shown by a solid line in FIG. 8)demanded of the control valve for use in a crutch-attached compressor.Therefore, it is now possible, through the provision of the restrictingmechanism (throttle aperture-attached closing member 70), not only torestrict the maximum flow rate of cooling medium to be fed to the crankchamber of compressor but also to substantially completely satisfy thecontrolling characteristics demanded of the control valve for use in thecrutch-attached compressor.

Furthermore, even in this embodiment, since the control valve can befabricated by simply attaching a restricting mechanism such as athrottle aperture-attached closing member 70 to the control valve for acrutch-less compressor, most of the control valves to be manufacturedfor use in a crutch-less compressor or a crutch-attached compressor canbe used not only for the crutch-less compressor but also for thecrutch-attached compressor, thereby making it possible to reduce themanufacturing cost of the control valve of the present invention.

By the way, in the foregoing embodiments, although the closing member 70having only one restricting through-hole 71 is employed as therestricting mechanism, the restricting mechanism is not limited to theclosing member 70 but can be variously modified. For example, theclosing member may be provided with a plurality of restricting apertureswherein the number of the restricting apertures and the size andconfiguration of each restricting aperture may be suitably selected aslong as a total opening area of these apertures can be confined smallerthan the maximum effective opening area of the valve aperture.

1. A method of manufacturing an assembled body composed of a pluralityof members including a metal member “A” made of a magnetic material anda metal member “B” made of a non-magnetic material, the methodcomprising the steps of: heating the metal member “A” and the metalmember “B” under conditions suitable for magnetic annealing of the metalmember “A” to braze the metal member “A” to the metal member “B” toobtain an assembled body comprising the metal member “A” and the metalmember “B”; and gradually cooling the assembled body to perform magneticannealing of the metal member “A”.
 2. The method according to claim 1,wherein the metal member “A” is brazed to the metal member “B” by makinguse of a brazing material having a melting point which is lower than amagnetic annealing temperature of the metal member “A”.
 3. The methodaccording to claim 1, wherein the metal member “A” is made of a magneticsteel such as an electromagnetic stainless steel, the metal member “B”is made of a non-magnetic steel material such as non-magnetic stainlesssteel, and the brazing material is made of copper wax or bronze wax. 4.The method according to claim 1, wherein the metal member “A” is formedof a step-attached columnar or cylindrical body having a diametrallycontracted end portion and a terrace surface, the metal member “B” isformed of a cylindrical body having an inner diameter which is largeenough to enable it to externally fit on the diametrally contracted endportion, the diametrally contracted end portion of the metal member “A”is provided, at an extended end portion thereof which is remote from theterrace surface, with an annular groove facing an inner peripheralsurface of the metal member “B” for holding a brazing material therein,and the brazing is performed under conditions wherein the metal member“B” is externally fitted on the diametrally contracted end portion withan fitted end of the metal member “B” being butted against the terracesurface and the brazing material being held between the annular grooveand the inner peripheral surface of the metal member “B”.
 5. The methodaccording to claim 1, wherein the metal member “A” is a stator of anelectromagnetic control valve, and the metal member “B” is a guide pipeto be used as a plunger guide of the electromagnetic control valve.
 6. Amethod for manufacturing an electromagnetic control valve provided withan assembled body comprising a stator made of a magnetic metallicmaterial, a guide pipe for use as a plunger guide which is fixedlycoupled to an lower end portion of the stator and made of a non-magneticmetallic material, a holder fixedly coupled to an lower end portion ofthe guide pipe and made of a metallic material, and a housing fixedlycoupled to the holder and made of a magnetic metallic material; whereinthe stator is formed of a step-attached columnar or cylindrical bodyhaving a diametrally contracted end portion and a terrace surface, theguide pipe is formed of a cylindrical body having an inner diameterwhich is large enough to enable it to externally fit on the diametrallycontracted end portion, the diametrally contracted end portion of thestator is provided, at an extended end portion thereof which is remotefrom the terrace surface, with an annular groove facing an innerperipheral surface of the guide pipe for holding a brazing materialtherein, the guide pipe is externally fitted on the diametrallycontracted end portion with an fitted end of the guide pipe being buttedagainst the terrace surface to thereby temporarily interconnect thestator, the guide pipe, the holder and the housing, the brazing materialis held between the annular groove and the inner peripheral surface ofthe guide pipe; the method being characterized in that it comprises thesteps of heating the temporarily interconnected assembled body underconditions for effecting magnetic annealing of the magnetic metallicmaterial such as the stator; and gradually cooling the assembled body toperform magnetic annealing of the stator, the holder and the housing. 7.The method according to claim 6, wherein the housing is fabricated intoa configuration enabling the housing to be press-inserted into theholder, the holder and housing are subjected to nickel plating or chromeplating, and the plated housing is press-inserted into the holder,thereby fabricating the temporarily interconnected assembled body. 8.The method according to claim 6, wherein the holder is formed into astep-attached cylindrical body to thereby enable the guide pipe to besnugly inserted therein, and the fabrication of the temporarilyinterconnected assembled body is performed by inserting the guide pipeinto the holder and, at the same time, by disposing the brazing materialat an interface between the inserted portion of the guide pipe and theholder.
 9. An electromagnetic control valve to be manufactured by themethod according to claim
 6. 10. A control valve for a variable capacitycompressor, which comprises: a valve rod having a valve body; a valvemain body provided with a valve chamber having a valve aperture withwhich the valve body can be retractivebly contacted, with an inlet portfor cooling medium of discharge pressure which is disposed on anupstream side of the valve aperture, and with a cooling medium outletport which is disposed on a downstream side of the valve aperture andcommunicated with a crank chamber of the compressor; an electromagneticactuator for driving the valve rod to move in the direction of openingor closing the valve aperture; and a pressure sensitive moving memberfor driving the valve rod to move in the direction of opening or closingthe valve aperture in response to a sucking pressure of the compressor;wherein the cooling medium outlet port is further provided with arestricting mechanism for restricting a maximum flow rate of the coolingmedium to be fed to the crank chamber.
 11. The control valve for avariable capacity compressor according to claim 10, wherein therestricting mechanism is constituted by a restricting pore-attachedclosing member which is secured to the cooling medium outlet port. 12.The control valve for a variable capacity compressor according to claim10, wherein the restricting mechanism is designed to regulate themagnitude of opening of valve in order to inhibit changes in gradient ofcontrolling pressure.
 13. The control valve for a variable capacitycompressor according to claim 12, wherein the magnitude of lift of thevalve body from the valve aperture is regulated for regulating themagnitude of opening of valve.
 14. A crutch-attached compressorcomprising the control valve for a variable capacity compressor which isclaimed in claim
 10. 15. A control valve for a variable capacitycompressor, which comprises: a valve rod having a valve body; a valvemain body provided with a valve chamber having a valve aperture withwhich the valve body can be retractivebly contacted, with an inlet portfor introducing cooling medium of discharge pressure from a compressor,the inlet port being disposed on an upstream side of the valve aperture,and with a cooling medium outlet port which is disposed on a downstreamside of the valve aperture and communicated with a crank chamber of thecompressor; an electromagnetic actuator constituted by a coil, acylindrical stator disposed on the inner peripheral side of the coil, asucking member secured to the stator, and a plunger disposed below thesucking member and enabled to slide up and down; a pressure sensitivechamber which is formed on the inner peripheral side of the stator andover the sucking member and to which an inlet pressure is introducedtherein from the compressor; a pressure sensitive driving memberdisposed in the pressure-sensitive chamber; and an operating rodinterposed between a pressure sensitive driving member and the plunger;wherein the valve body is designed to be moved in the valve-closingdirection as the plunger is moved close to the sucking member and in thevalve-opening direction as the operating rod is pushed downward by theactuation of the pressure sensitive driving member; and the coolingmedium outlet port is further provided with a restricting mechanism forrestricting a maximum flow rate of the cooling medium to be fed to thecrank chamber.
 16. The control valve for a variable capacity compressoraccording to claim 15, wherein the restricting pore-attached closingmember is provided with one or a plurality of restricting pores, a totalarea of aperture of the restricting pore-attached closing member is lessthan a maximum effective aperture area of the valve aperture.
 17. Thecontrol valve for a variable capacity compressor according to claim 15,wherein the restricting mechanism is constituted by a restrictingpore-attached closing member which is secured to the cooling mediumoutlet port.
 18. The control valve for a variable capacity compressoraccording to claim 15, wherein the restricting mechanism is designed toregulate the magnitude of opening of valve in order to inhibit changesin gradient of controlling pressure.
 19. The control valve for avariable capacity compressor according to claim 18, wherein themagnitude of lift of the valve body from the valve aperture is regulatedfor regulating the magnitude of opening of valve.
 20. A crutch-attachedcompressor comprising the control valve for a variable capacitycompressor which is claimed in claim 15.